The present invention is generally related to control systems and techniques for controlling compression-ignition engines, and, more particularly, this invention is related to a control system and method for reducing exhaust emissions and containing cylinder peak pressure particularly when the engine operates during high load conditions at a low ambient temperature.
Relatively large compression-ignition engines, such as those used for locomotives or power generation systems, are usually operated at full load with cylinder peak pressure (p.sub.p) close to but not exceeding a maximum structurally allowable value (p.sub.max). As ambient conditions change, such as when ambient temperature (T.sub.a) drops below a standard design point, e.g., a nominal operating temperature, and with ambient pressure (p.sub.a) remaining unchanged at a nominal value, p.sub.p increases and could exceed p.sub.max, resulting in undesirable increases in engine component stress and loading. Unfortunately, known techniques for avoiding a high p.sub.p, such as retarding fuel injection timing and reducing power output, are believed to undesirably deteriorate engine fuel efficiency and reduce engine power capability.
In view of the foregoing considerations, it is desirable to provide a system and method for controlling turbocharged compression-ignition engines to reduce exhaust emissions and contain cylinder peak pressure within structurally allowable limits, particularly during high load conditions at a low ambient temperature with minimal deterioration in engine efficiency and power capability.